WHAT THE FU? Mark Sanchez, sporting a glorious Fu Manchu mustache, was able to smile despite several miscues while rookie Geno Smith (left inset), his Jets QB competition, sat out the 37-13 preseason win over the Jaguars with a taped ankle.Neil Miller (2)

The Connecticut nanny accused of murdering the owner of a placement agency went ballistic because she believed she was being “blackballed” – and threatened to extract revenge a week before the slaying, according to court documents.

“I kept giving you a chance,” Flora Canales, the baby sitter and maid, allegedly whined to Alicia Kirkel as she fired shot after shot inside the offices of Royal Domestics in Greenwich.

Canales, 50, thought Kirkel, 41, was conspiring against her and told her building super that the Royal Domestics owner had “screwed up her life” for four years, according to the arrest affidavit.

“Mrs. Canales somehow felt blackballed by either the victim or Royal Domestics,” said Police Capt. David Ridberg. “It appears she had some business beef with the agency or the victim because she felt they were keeping her from getting work.”

Canales, who came to the United States from Guatemala 20 years ago, told the super, Paul O’Bday last week that she planned to kill the owner of an employment agency, the affidavit said.

O’Bday thought she was “just blowing off steam,” but Canales was apparently deadly serious.

On Monday morning, she stormed into Royal Domestics, confronted Kirkel in front of three women filling out applications, pulled a small black revolver from her purse and opened fire, cops said.

At a hearing yesterday, the suspect was ordered held on $500,000 bail.